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   <title>Jakarta Lucene API</title>
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Jakarta Lucene is a high-performance, full-featured text search engine library.
The API is divided into several packages:

<ul>
<li>
<b><a href="org/apache/lucene/util/package-summary.html">org.apache.lucene.util</a></b>
contains a few handy data structures, e.g., <a href="org/apache/lucene/util/BitVector.html">BitVector</a>
and <a href="org/apache/lucene/util/PriorityQueue.html">PriorityQueue</a>.</li>

<li>
<b><a href="org/apache/lucene/store/package-summary.html">org.apache.lucene.store</a></b>
defines an abstract class for storing persistent data, the <a href="org/apache/lucene/store/Directory.html">Directory</a>,
a collection of named files written by an <a href="org/apache/lucene/store/OutputStream.html">OutputStream</a>
and read by an <a href="org/apache/lucene/store/InputStream.html">InputStream</a>.&nbsp;
Two implementations are provided, <a href="org/apache/lucene/store/FSDirectory.html">FSDirectory</a>,
which uses a file system directory to store files, and <a href="org/apache/lucene/store/RAMDirectory.html">RAMDirectory</a>
which implements files as memory-resident data structures.</li>

<li>
<b><a href="org/apache/lucene/document/package-summary.html">org.apache.lucene.document</a></b>
provides a simple <a href="org/apache/lucene/document/Document.html">Document</a>
class.&nbsp; A document is simply a set of named <a href="org/apache/lucene/document/Field.html">Field</a>'s,
whose values may be strings or instances of <a href="http://java.sun.com/products/jdk/1.2/docs/api/java/io/Reader.html">java.io.Reader</a>.</li>

<li>
<b><a href="org/apache/lucene/analysis/package-summary.html">org.apache.lucene.analysis</a></b>
defines an abstract <a href="org/apache/lucene/analysis/Analyzer.html">Analyzer</a>
API for converting text from a <a href="http://java.sun.com/products/jdk/1.2/docs/api/java/io/Reader.html">java.io.Reader</a>
into a <a href="org/apache/lucene/analysis/TokenStream.html">TokenStream</a>,
an enumeration of&nbsp; <a href="org/apache/lucene/analysis/Token.html">Token</a>'s.&nbsp;
A TokenStream is composed by applying <a href="org/apache/lucene/analysis/TokenFilter.html">TokenFilter</a>'s
to the output of a <a href="org/apache/lucene/analysis/Tokenizer.html">Tokenizer</a>.&nbsp;
A few simple implemenations are provided, including <a href="org/apache/lucene/analysis/StopAnalyzer.html">StopAnalyzer</a>
and the grammar-based <a href="org/apache/lucene/analysis/standard/StandardAnalyzer.html">StandardAnalyzer</a>.</li>

<li>
<b><a href="org/apache/lucene/index/package-summary.html">org.apache.lucene.index</a></b>
provides two primary classes: <a href="org/apache/lucene/index/IndexWriter.html">IndexWriter</a>,
which creates and adds documents to indices; and <a href="org/apache/lucene/index/IndexReader.html">IndexReader</a>,
which accesses the data in the index.</li>

<li>
<b><a href="org/apache/lucene/search/package-summary.html">org.apache.lucene.search</a></b>
provides data structures to represent queries (<a href="org/apache/lucene/search/TermQuery.html">TermQuery</a>
for individual words, <a href="org/apache/lucene/search/PhraseQuery.html">PhraseQuery</a>
for phrases, and <a href="org/apache/lucene/search/BooleanQuery.html">BooleanQuery</a>
for boolean combinations of queries) and the abstract <a href="org/apache/lucene/search/Searcher.html">Searcher</a>
which turns queries into <a href="org/apache/lucene/search/Hits.html">Hits</a>.
<a href="org/apache/lucene/search/IndexSearcher.html">IndexSearcher</a>
implements search over a single IndexReader.</li>

<li>
<b><a href="org/apache/lucene/queryParser/package-summary.html">org.apache.lucene.queryParser</a></b>
uses <a href="http://javacc.dev.java.net">JavaCC</a> to implement a
<a href="org/apache/lucene/queryParser/QueryParser.html">QueryParser</a>.</li>
</ul>
To use Lucene, an application should:
<ol>
<li>
Create <a href="org/apache/lucene/document/Document.html">Document</a>'s by
adding
<a href="org/apache/lucene/document/Field.html">Field</a>'s.</li>

<li>
Create an <a href="org/apache/lucene/index/IndexWriter.html">IndexWriter</a>
and add documents to to it with <a href="org/apache/lucene/index/IndexWriter.html#addDocument(org.apache.lucene.document.Document)">addDocument()</a>;</li>

<li>
Call <a href="org/apache/lucene/queryParser/QueryParser.html#parse(java.lang.String)">QueryParser.parse()</a>
to build a query from a string; and</li>

<li>
Create an <a href="org/apache/lucene/search/IndexSearcher.html">IndexSearcher</a>
and pass the query to its <a href="org/apache/lucene/search/Searcher.html#search(org.apache.lucene.search.Query)">search()</a>
method.</li>
</ol>
Some simple examples of code which does this are:
<ul>
<li>
&nbsp;<a href="../../src/demo/org/apache/lucene/demo/FileDocument.java">FileDocument.java</a> contains
code to create a Document for a file.</li>

<li>
&nbsp;<a href="../../src/demo/org/apache/lucene/demo/IndexFiles.java">IndexFiles.java</a> creates an
index for all the files contained in a directory.</li>

<li>
&nbsp;<a href="../../src/demo/org/apache/lucene/demo/DeleteFiles.java">DeleteFiles.java</a> deletes some
of these files from the index.</li>

<li>
&nbsp;<a href="../../src/demo/org/apache/lucene/demo/SearchFiles.java">SearchFiles.java</a> prompts for
queries and searches an index.</li>
</ul>
To demonstrate these, try something like:
<blockquote><tt>> <b>java -cp lucene.jar:lucene-demo.jar org.apache.lucene.demo.IndexFiles rec.food.recipes/soups</b></tt>
<br><tt>adding rec.food.recipes/soups/abalone-chowder</tt>
<br><tt>&nbsp; </tt>[ ... ]
<p><tt>> <b>java -cp lucene.jar:lucene-demo.jar org.apache.lucene.demo.SearchFiles</b></tt>
<br><tt>Query: <b>chowder</b></tt>
<br><tt>Searching for: chowder</tt>
<br><tt>34 total matching documents</tt>
<br><tt>0. rec.food.recipes/soups/spam-chowder</tt>
<br><tt>&nbsp; </tt>[ ... thirty-four documents contain the word "chowder",
"spam-chowder" with the greatest density.]
<p><tt>Query: <b>path:chowder</b></tt>
<br><tt>Searching for: path:chowder</tt>
<br><tt>31 total matching documents</tt>
<br><tt>0. rec.food.recipes/soups/abalone-chowder</tt>
<br><tt>&nbsp; </tt>[ ... only thrity-one have "chowder" in the "path"
field. ]
<p><tt>Query: <b>path:"clam chowder"</b></tt>
<br><tt>Searching for: path:"clam chowder"</tt>
<br><tt>10 total matching documents</tt>
<br><tt>0. rec.food.recipes/soups/clam-chowder</tt>
<br><tt>&nbsp; </tt>[ ... only ten have "clam chowder" in the "path" field.
]
<p><tt>Query: <b>path:"clam chowder" AND manhattan</b></tt>
<br><tt>Searching for: +path:"clam chowder" +manhattan</tt>
<br><tt>2 total matching documents</tt>
<br><tt>0. rec.food.recipes/soups/clam-chowder</tt>
<br><tt>&nbsp; </tt>[ ... only two also have "manhattan" in the contents.
]
<br>&nbsp;&nbsp;&nbsp; [ Note: "+" and "-" are canonical, but "AND", "OR"
and "NOT" may be used. ]</blockquote>
The <a href="../../src/demo/org/apache/lucene/demo/IndexHTML.java">IndexHtml</a> demo is more sophisticated.&nbsp;
It incrementally maintains an index of HTML files, adding new files as
they appear, deleting old files as they disappear and re-indexing files
as they change.
<blockquote><tt>> <b>java -cp lucene.jar:lucene-demo.jar org.apache.lucene.demo.IndexHTML -create java/jdk1.1.6/docs/relnotes</b></tt>
<br><tt>adding java/jdk1.1.6/docs/relnotes/SMICopyright.html</tt>
<br><tt>&nbsp; </tt>[ ... create an index containing all the relnotes ]
<p><tt>> <b>rm java/jdk1.1.6/docs/relnotes/smicopyright.html</b></tt>
<p><tt>> <b>java -cp lucene.jar:lucene-demo.jar org.apache.lucene.demo.IndexHTML java/jdk1.1.6/docs/relnotes</b></tt>
<br><tt>deleting java/jdk1.1.6/docs/relnotes/SMICopyright.html</tt></blockquote>
HTML indexes are searched using SUN's <a href="http://jserv.javasoft.com/products/webserver/index.html">JavaWebServer</a>
(JWS) and <a href="../../src/demo/Search.jhtml">Search.jhtml</a>.&nbsp; To use
this:
<ul>
<li>
copy <tt>Search.html</tt> and <tt>Search.jhtml</tt> to JWS's <tt>public_html</tt>
directory;</li>

<li>
copy lucene.jar to JWS's lib directory;</li>

<li>
create and maintain your indexes with demo.IndexHTML in JWS's top-level
directory;</li>

<li>
launch JWS, with the <tt>demo</tt> directory on CLASSPATH (only one class
is actually needed);</li>

<li>
visit <a href="../../src/demo/Search.html">Search.html</a>.</li>
</ul>
Note that indexes can be updated while searches are going on.&nbsp; <tt>Search.jhtml</tt>
will re-open the index when it is updated so that the latest version is
immediately available.
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